New find pushes age of stone tools back a million years

Hominins have been using stone tools for at least 3.4 million years, about 900 …

The genus Homo is no longer the sole primate lineage known to have used stone tools to consume the meat of large mammals. New research pushes that skill back nearly a million years.

Large fossilized animal bones with ends shattered for sucking out marrow and cut marks deliberately made with sharp stone tools have been found just a few hundred feet from a previously uncovered Australopithecus aferensis skeleton. The bones are roughly 3.4 million years old, and connect the earliest evidence for using stone tools and eating large game to our Lucy-like ancestors.

Previously, the earliest evidence for using tools to cut the meat off large animals was attributed to early Homo in the Gona region of Ethiopia around 2.5 million years ago. This find from a different region in Ethiopia, Dikika, shows the behavior was around at least a million years earlier.

'It means almost everything to be able to use stone tools," said paleontologist Zeray Alemseged of the California Academy of Sciences, co-author of the discovery announced August 12 in Nature. "The picture that we're going to paint of Australopithecus is being transformed completely. We can now imagine them walking around carrying their tools. Tools that were the precursor of every tool that we have today."

"Australopithecus was a very primitive, ape-like early human," said biological anthropologist Craig Stanford at University of Southern California, who edited a book on meat eating and human evolution. "The fact that they were using tools and eating meat indicates this was something that was widespread very early in human history."

Two parallel cutmarks made by stone tools on the rib of a cow-sized mammal

Image credit: Dikika Project

The ability to carve meat off large mammal carcasses likely put Australopithecus in competition with dangerous scavengers, Alemseged says. It is unlikely they were hunting for the large game because their body shape would not have allowed them to run fast, which is necessary to chase down an antelope or similar sized animal.

But scavenging large animals still provides access to high quality, high calorie foods that likely enabled Australopithecus to venture much further out of the forest environment into the open grassland than otherwise possible on a diet of mostly of fruit, leaves and tubers.

The two cut bones found both came from mammals. One is a rib from a cow-sized animal, and the other is a femur shaft from an antelope-sized animal. Analysis of the bones showed the cut marks were created before the bones fossilized, eliminating the possibility the marks were made recently.

While it is impossible to tell from the scratches whether Australopithecus was making stone tools or using naturally sharp rocks, the lack of adequate rock material in the immediate area where the bones were found suggests they were carrying the stones around with them from one place to another.

However, no one has yet found the stone tools themselves or where they could have come from, and at least one scientist finds this reason to be skeptical of the claims made by the discoverers.

"The fact that no single sharp-edged flaked stone has been recovered from the site makes such a claim doubtful of any hominid involvement," said paleontologist Sileshi Semaw of the Stone Age Institute, who discovered what was previously the oldest evidence for stone tool from the Gona region. "Researchers who study bone surface modifications from archeological sites have shown that fresh bones trampled by animals can create marks that mimic stone tool cut marks."

"The next stage will be to really go out there and scrutinize the site to see if the tools are indeed there," said Alemseged in response. "But I wouldn't be surprised if the stone tools were archeologically invisible to us. They might have been using the tools in a sporadic way."

26 Reader Comments

Check out the current (or one month back) issue of National Geographic for a really good review of all the various African hominid discoveries, dates, and relations, as scientists currently understand them.

I'm kinda hoping this gets confirmed by finding actual 3-million year old tools, rather than disproven by showing them to be marks left by something else. This month's Scientific American also ran a piece that explains why some anthropologists are willing to push back the flowering of art in Homo sapiens back tens of thousands of years and to the southern-most tip of Africa, compared to the later dates we know from sites in Europe. The development of humanity just gets more and more fascinating.

If the area was as resource-poor as described in the original article, then the hominids would have curated the tools (or sharp rocks) for future use rather than tossing them away.

So, I think that Semaw's objections about no tools being found at the Dikika site are due to a case of sour grapes.

Yes, but during that whole time hunting...ONE of them must have died, or a bit of his tools left behind, or something. Not finding any evidence just keeps this a bit suspect.

Usually they'll butcher the animal on the spot to decrease the load you carry back. And while doing so, there'd be remains of them "re-sharpening" their tools by chipping them a few more times to get another sharp cutting edge.

When you find bones like this sitting around, that look like they've been carved into, smashed, etc ... but no stone fragments around...it's just bizarre.

If the area was as resource-poor as described in the original article, then the hominids would have curated the tools (or sharp rocks) for future use rather than tossing them away.

So, I think that Semaw's objections about no tools being found at the Dikika site are due to a case of sour grapes.

Yes, but during that whole time hunting...ONE of them must have died, or a bit of his tools left behind, or something. Not finding any evidence just keeps this a bit suspect.

Usually they'll butcher the animal on the spot to decrease the load you carry back. And while doing so, there'd be remains of them "re-sharpening" their tools by chipping them a few more times to get another sharp cutting edge.

When you find bones like this sitting around, that look like they've been carved into, smashed, etc ... but no stone fragments around...it's just bizarre.

You're assuming they were using flint tools, sharpened granite and sandstone tools are ground down not chipped.

You're assuming they were using flint tools, sharpened granite and sandstone tools are ground down not chipped.

Good point. Maybe the reason we don't have any evidence is because we're looking for the wrong thing. Could be that the really early tools could only be used several times before they became useless, or maybe (as you suggest) they were made of sandstone and have weathered or disintegrated over the last 3.5 million years.

Just like that group of chimps developed a culture of washing food before eating it, maybe we evolved the way we did because of a fluke that gave the Australopithecus' a culture of being able to cut meat, which was refined over time to the stone tools we're more familiar with. I find this stuff so fascinating.

Yes, but during that whole time hunting...ONE of them must have died, or a bit of his tools left behind, or something. Not finding any evidence just keeps this a bit suspect.

I don't think hunting cows or antelope would always result in someones death. In fact if they were successful hunters they would know how to stay safe and hunt efficiently. It's not like they hunted woolly mammoth and sabre toothed tigers all day.

If the area was as resource-poor as described in the original article, then the hominids would have curated the tools (or sharp rocks) for future use rather than tossing them away.

So, I think that Semaw's objections about no tools being found at the Dikika site are due to a case of sour grapes.

Yes, but during that whole time hunting...ONE of them must have died, or a bit of his tools left behind, or something. Not finding any evidence just keeps this a bit suspect.

NOT finding anything is the norm. Consider how long it has taken to find the few remains from that era... Generations of archeological work, and we didn't find these two small bones untill now. Sure they might be wrong, but I don't see why the find becomes so suspect because it isn't more complete. 3.4 million years is a LONG time!

Also consider that tool construction is emphatically not part of the claim. On the contrary it is suggested that they might have used naturally ocurring sharp stones (which seems more than likely for the earliest stonetools). That would exclude any kind of chips or fragments from tool production as well as any signs of "man"made modifications of the stone, and would probably make it a hell of a lot more dificult to identify their tools. Does a stone keep an edge for 3 million years? If not there would be absolutely nothing to identify it unless geologists have some usefull insights..

Two pictures to contradict hundreds of years of research? Please. Academic paper are proved wrong all the time. There are always many explanations to a single evidence.

Does it contradict hundreds of years of research? My understanding is that the fossils are evidence of something we didn't know or understand before - it doesn't contradict existing evidence, it expands on it.

It may turn out that the fossils aren't evidence of Australopithecus tool use, but the fossils as they stand don't contradict any previously existing evidence, they just counter previous conclusions. This is a Good Thing®

I wouldn't want to say that those are/are not marks from stone tools myself, but there is a great contemporary analog.

There are capuchin monkeys in the Amazon that use a hammer stone and anvil arrangement to break open palm nuts. The monkeys train for this skill for months or years before getting it right.

If a relatively primitive (compared to us) primate can do that, my guess (and only a guess) would be that there have been other primates who have used tools as well. We know humans like them, chimps use tools, and so do these guys.

too bad their steel knives all rusted away before we could find them...

You've got it completely wrong. It was visiting aliens on space-vacation that were eating space-beef ("cows") and they carelessly left their garbage behind. Of course, they took their space-knives with them when they left. Duh.